Adrenergic Drugs Overview

Medications that either mimic or block the effects of neurotransmitters like norepinephrine and epinephrine, which are involved in the 'fight or flight' response.

Drugs that stimulate adrenergic receptors, mimicking the effects of norepinephrine and epinephrine. They can be categorized based on the specific receptor subtype they target.

They primarily target blood vessels, the eye, and the urinary tract, causing vasoconstriction, pupil dilation, and smooth muscle contraction.

Phenylephrine is an alpha-1 agonist used to treat hypotension (low blood pressure).

They primarily affect the brainstem, inhibiting norepinephrine release and reducing sympathetic outflow. This leads to decreased blood pressure and sedation.

Clonidine is an alpha-2 agonist used to treat hypertension (high blood pressure) and withdrawal symptoms.

They primarily target the heart, increasing heart rate, contractility, and conductivity, thus improving cardiac output.

They primarily target the lungs, uterus, and vasculature, causing bronchodilation, vasodilation, and relaxation of uterine smooth muscle.

Drugs that block alpha-1 receptors on smooth muscle, causing vasodilation, reduced blood pressure, and relaxation of bladder/prostate muscle.

An alpha-1 antagonist used to treat hypertension and benign prostatic hyperplasia (BPH).

An alpha-1 antagonist primarily used to treat benign prostatic hyperplasia (BPH).

Drugs that block alpha-2 receptors, leading to increased norepinephrine release and potential blood pressure increase.

An alpha-2 antagonist used to treat erectile dysfunction and orthostatic hypotension.

Drugs that block beta-1 receptors on the heart, reducing heart rate, contractility, and cardiac output.

Common beta-1 blockers used for hypertension, arrhythmias, and heart failure.

Drugs that block both beta-1 and beta-2 receptors, affecting the heart, lungs, and vasculature.

Drugs that mimic or block the effects of acetylcholine, a neurotransmitter involved in the 'rest-and-digest' response.

They directly stimulate cholinergic receptors, either muscarinic or nicotinic, triggering the effects of acetylcholine.

Drugs that specifically stimulate muscarinic receptors found in organs like the heart, smooth muscles, and glands.

They act via M2 receptors, slowing the heart rate (bradycardia) and decreasing heart muscle contractility.

Drugs that directly activate nicotinic receptors, which are ion channels located at the neuromuscular junction (Nm receptors) and in autonomic ganglia (Nn receptors).

Upon Nn receptor stimulation, they increase both sympathetic and parasympathetic tone, depending on the organ system.

Nicotine, a nicotinic receptor agonist, stimulates both Nn and Nm receptors leading to CNS stimulation, increased heart rate, and increased blood pressure.

They stimulate the parasympathetic nervous system, leading to the 'rest-and-digest' response, such as slowing the heart rate and increasing digestive processes.

These drugs work by increasing the concentration of acetylcholine (ACh) at cholinergic synapses, usually by inhibiting the enzyme acetylcholinesterase, which breaks down ACh.

Drugs that inhibit the enzyme acetylcholinesterase (AChE), which breaks down acetylcholine. By preventing ACh breakdown, these drugs increase ACh's action at both muscarinic and nicotinic receptors.

These drugs form a covalent bond with acetylcholinesterase, leading to prolonged inhibition. They permanently inactivate AChE, leading to prolonged accumulation of ACh.

Irreversible inhibitors used in pesticides and chemical warfare agents. They cause prolonged ACh accumulation, leading to toxic effects like muscle paralysis and respiratory failure.

Drugs like pralidoxime can reactivate acetylcholinesterase that has been inhibited by organophosphates, reversing toxic effects.

A reversible inhibitor used to treat myasthenia gravis and reverse neuromuscular blockade during surgery.

A reversible inhibitor used to treat anticholinergic toxicity (e.g., atropine overdose) and glaucoma.

Reversible inhibitors used to treat Alzheimer's disease by increasing ACh levels in the brain.

Drugs previously used for emergency hypertension treatment but largely replaced due to their widespread and unpredictable effects on both sympathetic and parasympathetic nervous systems.

Drugs that block muscarinic receptors in the central nervous system (CNS) to treat specific conditions like motion sickness and Parkinson's disease.

Used to treat Parkinson's disease by blocking muscarinic receptors in the CNS, specifically the striatum, restoring balance between dopamine and acetylcholine.

Another drug for Parkinson's and antipsychotic-induced movement disorders, working by blocking muscarinic receptors.

These drugs primarily reduce parasympathetic nervous system activity, resulting in various physiological changes.

Increased heart rate due to reduced vagal tone (M2 receptor blockage) and potentially decreased cardiac output and blood pressure.

Bronchodilation (M3 receptor blockage) and dry mouth/throat due to reduced salivary gland activity.

Decreased motility and reduced gastric acid secretion due to M3 receptor blockade in the gastrointestinal tract.

Drugs that block the action of acetylcholine, a neurotransmitter involved in the parasympathetic nervous system. They mimic the effects of the sympathetic nervous system, leading to a 'fight or flight' response.

Cholinergic blockers cause a range of effects, such as increased heart rate, dilated pupils, reduced gastrointestinal motility, and decreased production of saliva and mucus.

They are a type of cholinergic blocker that selectively blocks muscarinic receptors, which are found in various organs throughout the body.

Atropine is a widely used antimuscarinic drug with diverse applications, including treatment of bradycardia, antidote for cholinergic poisoning, pupil dilation for eye exams, and pre-anesthetic medication.

Scopolamine is primarily used to prevent nausea and vomiting associated with motion sickness, but it also has applications in ophthalmology for pupil dilation.

These antimuscarinic bronchodilators are used to treat chronic obstructive pulmonary disease (COPD) and asthma by relaxing the muscles in the airways, making it easier to breathe.

They block the transmission of nerve impulses through autonomic ganglia by inhibiting nicotinic receptors, which are found on the nerve cell bodies.

Ganglionic blockers have significant side effects because they broadly affect both the sympathetic and parasympathetic nervous systems, leading to unpredictable and potentially dangerous outcomes.